The present invention relates to the detection and measurement of electric fields and more particularly to an improved fiber optic sensor system and associated technique wherein an optical fiber wrapped about a piezoelectric core is used for accurately detecting a measurable electric field.
In the measurement of an electric field environment, various electrical sensors have been employed to detect the presence and nature of an electric field. Many of these electrical sensors include the use of a pair of metal electrodes connected to an electrometer to measure a voltage therebetween. With the electrode separation being known, the electric field is equal to the measured voltage divided by the separation distance. Another common electrical sensor used in electric field detection and measurement includes a parallel plate capacitor which varies in capacitance value with time. A measure of the charge flowing into and out of the capacitor yields the associated voltage and thereby the electric field.
While these and other existing electrical sensors have generally been satisfactory in measuring the presence of most electric fields in an environment, they have not been entirely effective in accurately detecting relatively small fields due to limitations in their sensitivity and reliability. Firstly, all such electrical sensors are subject to noise pick-up in the cables leading to and from the sensors. Secondly, the intermetallic connections that exist in these sensors, particularly in the metal electrode type, act as thermocouple junctions to generate seemingly negligible currents and potentials that can cause significant errors in the measurement of small electric fields. Furthermore, these electrode-type sensors have not been capable of providing accurate and reliable measurements of electric fields in an ocean environment due to erroneous electro-potentials generated by the metal electrodes when immersed in sea water.